Styrenic polymers and especially acrylonitrile butadiene styrene (ABS)-based polymers are used in various applications such as for manufacturing light, rigid, molded products including luggage, appliance, and telephone housing, pipe, golf club, sporting helmet, automotive part, wheel cover, enclosure, protective head gear, cosmetic case, and toy. In general, polymer-based moldings readily generate static electricity and often collect dust from air while they are handled in storage, transported and used.
A common approach to improving the antistatic properties of thermoplastics involves using internal antistatic agents incorporated into the thermoplastic polymeric materials by compounding or extrusion prior to or during the manufacture of items, for example, by means of molding or film-forming processes. Such antistatic agents, including a broad range of chemical classes (e.g., ethoxylated amine chemicals and homopolymers and copolymers of ethylene oxide, esters of fatty acids, carbon black and surfactants), work by migrating to the external polymer surface of the manufactured articles. These antistatic agents are very volatile and form a continuous film on the external polymer surface of the manufactured item because of its limited compatibility with the polymer composition itself. Therefore, the further processability of the manufactured item can become problematic. For example, the surface of the manufactured item may become sticky or stained by bleeding of the antistatic agent, leading to an unaesthetic appearance. Subsequent processing on the manufactured item, such as printing, cannot be readily done because a certain time, up to one week, is required for allowing proper migration of the antistatic agents. During that time, problems related to the adhesion of the printing may arise due to dust accumulation on the surface of the article, so that an additional pre-treatment step to remove this dust before handling the article is required. Deterioration in time of the antistatic effect is also usually observed due to the fact that the antistatic agents are directly exposed to the external environment.
To prevent the accumulation of static charges on the surface of molded articles, films or sheets, as well as to improve the drawback of migrating antistatic agents, permanent antistatic agents have been developed. See, e.g., WO2005/075556, JP H10-193495A, JP H11-077928, JP H08-134295, JP H10-060185, and JP H10-060186.
Though compositions comprising potassium ionomers with or without polyols may have acceptable antistatic properties, such compositions have reduced mechanical properties including low impact strength, which can cause the brittleness of any article made of such compositions.
There is therefore a current need for styrenic polymer compositions having acceptable antistatic properties and reduced dust absorption while maintaining or even enhancing mechanical properties of the polymer.